I need to measure level of vertical tank of 4mtr with bottom cone comprising of slurry with mixed acid' Nitric acid & Sulfuric acid which is being agitated that also causes fume generation. We have used contact less radar type transmitter, but due to fumes there is a jelly formation on the sensor and thus doesn't work as intended.
Also, due to changing density i cannot use DP type transmitter.
Sp. grav variations don't rule out d/p measurements necessarily.
Two d/p measurements are required on for gravity, the second for level, with the s.g. correction in your dcs.
You can direct connect to the process with chem seals or use bubblers with compatible gas.
You want something that works and easy for your crews to trouble-shoot, a practical solution.
The laser level transmitter is an other good option for this application. A example of products ...
ABB offers the standard KM26 Magnetic Level Gauge with a chamber of virtually any non-magnetic material, extruded process connections, a custom engineered float and all accessories with 316 stainless steel construction. The ABB MagWave dual chamber redundant level system has a proven record of improving feedwater heater reliability in power plants around the world. The MagWave combines a highly visible magnetic level indicator with the precise level measurement of a guided wave radar transmitter. Redundant level control can be achieved by adding a magnetostrictive transmitter or switch to the float chamber.
What's the density of the foam? Maybe you need to have a look at the radar configuration (echoes curve). If the density is not high, it should work correctly! Otherwise, you can go to guided radar or laser level transmitter.
I'm guessing with that witches brew you have a lined vessel. The Agitator further complicates things.
My suggestion would be use the non contact radar you now have (I assume it does work), but figure out how you can prevent the jelly build-up perhaps an air purge or intermittent spray. It might even be possible to have the radar protected by a Teflon window.
Another thought depending on how accurate you need is to add another blade on the agitator above the normal level then monitor agitator power. If the level reaches the second set of blades, the power will go up significantly.
You didn't say if it's a batch or continuous process.